Attorney Marc Toberoff cooperated with prosecutors after he said privileged documents concerning his efforts to help survivors of the creators of Superman gain rights to the famous comic character were stolen by another lawyer then working for him. But because of that he has lost his legal battle to prevent a litigation opponent from using the material.

A “selective waiver” of the attorney-client privilege that might otherwise apply allows Warner Bros. to make use of the documents in a tortious interference suit against Toberoff, the San Francisco-based 9th U.S. Circuit Court of Appeals ruled Tuesday.

The studio, which allegedly received the documents from Toberoff’s ex-employee, is contending that Toberoff interfered with its relationship with the survivors.

In an opinion (PDF) authored by Judge Diarmuid O’Scannlain, the court also suggested that Toberoff and his firm might have been acting as a business adviser rather than legal counsel in the matter, according to the Hollywood Reporter’s Hollywood, Esq. blog.

“We cooperated with the U.S. Attorney’s office to enable them to investigate the theft from our law firm of the Siegels and Shuster’s privileged documents,” Toberoff said in a written statement, referring to the survivors of the Superman creators. “We are disappointed in today’s decision which holds that such cooperation with law enforcement by the victims of a privacy crime itself waives privilege as to stolen documents. However, nothing in this ruling or the documents at issue will affect the merits of this case. We are considering our options as to the ruling and will continue to vigorously defend our clients’ rights.”

Warner Bros. said in a statement that the studio is extremely pleased with the ruling.

Related coverage:

Hollywood, Esq: “Hollywood Heist: How a Burglary May Impact the Future Of ‘Superman’ (Analysis)”

Updated at 6:53 p.m. to link to earlier Hollywood, Esq. article and at 7:06 p.m. to include additional information from Hollywood, Esq.